The invention relates to a pump for conveying a medium, in particular hydraulic oil, and comprising a flow controller for controlling the flow of medium conveyed by the pump through a discharge channel releasable by a flow-control valve.
Such pumps are known and are used, for example, in motor vehicles for power-steering and/or brake-servo systems as well as for hydraulic suspension systems or the like. This involves pumps which are driven directly by the internal-combustion engine and which thus have a volume flow variable as a function of the rotational speed of the engine or a conveying capacity dependent upon the rotational speed. In those cases in which the consumer connected to the pump requires only a specific maximum volume flow, a flow-control valve is provided which limits the flow of medium delivered by the pump to the consumer. If the conveying capacity of the pump exceeds the maximum volume flow, the flow-control valve opens a discharge channel, by way of which the medium conveyed by the pump flows back to the suction side of the pump. It has been found that in many cases damage is caused at high rotational speeds by cavitation. In addition, there is an irregular suction performance of the pump.